I have a 5 year old samsung 4k with a samsung sound bar. ARC does not work reliably. It did but just stops working. I have to power cycle the TV. Change HDMI cables etc. All the normal I am an engineer, made check list, swapped parts in controlled manor stuff. Even tried another soundbar that works fine on another set. Googling tells me other have this issue and samsung does not care as it is to old (it is likely sw issue). TV is going to be replaced with much more expensive Sony as they still seem to take pride in their product quality. Oh as to the ads, never hook TV up to internet. I use an AppleTV and it just works.
I want ARC/CEC to work as I want a single remote. You loose that when using optical.
If optical works reliably, you could possibly leave both HDMI and optical plugged in to the sound bar. CEC volume control and power seems to still work with my sound bar when set to the optical input.
My setup currently has an audio drop out every few minutes. It seems to happen over both ARC and optical, though, so it's presumably just the Nvidia Shield being buggy. The UI bugs out too lately. I've had various forms of audio drop outs on that TV since at least 2020. It could be the TV corrupting the passthrough I guess. I'm not going to buy a whole new TV just to test that hypothesis.
I want ARC/CEC to work as I want a single remote. You loose that when using optical.